Vania



(Nd Model.)

H. N. POTTER.

FUSE BLOCK.

Patented-Sept. 17, 1895.

/NVENTOH I ATTORNEYS.

ANDREW B GRANAMJHOYOMYHQWASHINGTON. D c

UNTEEE STATEsATENT @EETCEQ HENRY NOEL POTTER, OF ALLEGHENY, AssiGNoR TO THE WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, OF PITTSBURG, PENNsYL- ANIA.

FUSE-BLOCK.

SPECIFICATION forming part of Letters Patent No. 546,475, datedseptember 17, 1895.

Application filed October 1'7, 189%- Serial No. (N model-l To all whom it may concern. use for like purposes. By this arrangement Be it known that l, HENRY NOEL POTTER, the fuse may be of such size that it would carry a citizen of the United States, residing in Al-' the melting-current without blowing if used legheny, in the county of Allegheny and State without the heating-coil. This heating-con- 55 of Pennsylvania, have invented a new and ductor I locate in proximity to the fuse and useful Improvement in Fuse-Blocks, (Case in electrical connection therewith, so that the No. 615,) of which the following is aspecificaheat generated therein may be transmitted to tion. thefuse'through whatever medium may be My invention relates to that class of devices interposed between the said devices. By such 60 [O commonly known as fuse-blocks, which are a combination and arrangement of parts, it is employed in connection with electric circuits clear that any increase in current in the heatfor the purpose of automaticallyinterrupting ing-coil will cause a much more than proporthe same whenever the current increases to tional increase in the temperature by reason such a degree as to endanger the translating of the large temperature-resistance coefficient 65 devices fed thereby; and it has forits'object to of the material of which it is composed. The

provide a device of this character which will heat thus generated will be instantly and dioperate in such a manner as to maintain the rectly transmitted to the fusible strip, thus fuse unimpaired during the passage of a norraising its temperature at a rate and to a de malcurrent, and which will insure the immegree greatly in excess of the rate and degree 70 diate blowing of the fuse whenever an excess which could occur under any conditions of of current relatively small, as compared with self-heating, because of the comparatively inthat required to blow ordinary fuses of equal significant temperatureresistance coefficient conducting capacity, occurs. In order to seof any of the fuse-alloys or even of pure lead. cure the best results with devices of this char- In the accompanying drawing I have shown 7 5 2 5 acter, it is necessary that the fuse shall carry an electric circuit and a fuse-block which is a normal current indefinitely Without deteriillustrative of my invention in connection oration, and that it shall blow within a brief therewith, the former being shown diagraminterval of time whenever there is a dangermatically and the latter partially in section ous increase of current beyond the normal. and partially in plan. 80 0 Experience has demonstrated that an ordi- Referring to the drawing in detail, 1 is a nary lead fuse, or one composed of any of the suitable electric generator and 2 represents commercial alloys which Will melt within a a series of translating devices. Connected reasonable time under the direct heating efwith one branch of the generator or circuit, fects of a given electric current-,will not carry by means ofa binding-post 3, is one end of a 8 5 5 much more than one-third of such current for fusible wire or strip 4, such wire or strip beany considerable period of time Without maing composed of any desired material comterial deterioration from oxidation and other monly employed in such connections and of causes. Such impaired condition of the fuse, any desired form. The other end of this fusidue to currents of less than sufficient quantity ble strip is connected, by means of a binding- 0 40 to melt the same, results in many secondary post 5, to one end of a coil of iron wire 6, the attendant inconveniences known to those said coil being, in the present instance, shown skilled in the art, and it is the purpose of the as Wrapped about the fuse 4 and connected present invention to reduce to a minimum at the end opposite the binding-post 5 in cirsuch condition and attendant inconveniences cuit with the"generator 1 and translating de- 5 by generating the heat for blowing the fuse Vices 2 by means of a binding-post 7. Ihave in a conductor having a high temperature-respecified iron as the "material of which the sistance coefficient and a high melting-point, wire 6 is composed, because it has the highest and by using in connection therewith a fusicoefficient of increase of resistance per unit ble strip composed of material the meltingof increase of temperature, and for that rea- I00 point of which is as low as, or lower than, son it is the most suitable for this purpose. that of any of the metals or alloys in ordinary Any of the pure metals, however, have a sufficiently large temperature-resistance coefficient to permit of their use in this connection, but with less desirable results. Interposed between the fuse 4 and the coil 6 is a body of non-combustible insulating material 8, the said material having the form of a tube surrounding the fuse when the form and relation of the several parts of the device are as indicated in the drawing. I have found asbestos a suitable material to be employed in this connection; but any other material having the properties specified above may be employed, if desired. Surrounding the coil 6 and the fuse 4c is a casing or sheath 9, composed of non-conducting material, which is designed to serve merely as a protective covering for the said parts, the form and dimensions of which may be varied to conform to the wishes of the constructor.

It is to be understood that the particular form of connection between the fuse and the heating-coil, as well as that between the main circuit and the said devices, is immaterial, so far as my invention is concerned; and it is also to be understood that the form and relative location of the heating coil and fuse may be varied, as desired, the particular form shown and described being intended merely as illustrative of the broad principle of the invention.

Any increase of current through the fuse block will raise the temperature of the heating-coil 6, which will increase its resistance, and this increase in resistance will in turn further raise the temperature until the critical point is reached, when the heat transmitted from the coil 6 through the insulating material 8 will melt fuse 4: and interrupt further current flow.

My invention is particularly well adapted for use in connection with fuses which are intended to be blown by small currents, plain lead fuses for such currents being impracticable, owing to their necessarily small size and consequent mechanical weakness. In the present device the fuse may be made of the necessary strength, for the reason that the source of heat is external thereto.

What I claim is 1. In a fuse block, a fuse and a heating coil surrounding the same and in series therewith, substantially as described.

2. A fuse and insulating material surrounding the same, combined with a heating coil surrounding said insulating material and in series with said fuse, substantially as described.

In a fuse block, a fuse, an iron wire coil surrounding the same and in series therewith, and insulating material interposed between said coil and fuse,substantially as described.

4. A fuse block comprising a heat generating conductor formed of material having a high temperature resistance coefficient and an adjacent conductor formed of material fusible at a comparatively low temperature in series therewith, substantially as described.

5. A fuse block comprising a fuse, an adjacent heat generating conductor electrically connected in series therewith, interposed non conducting material and an insulating shell or casing, substantially as described.

In testimony whereof I have hereunto subscribed my name this 13th day of October, A. D. 189i.

Witnesses:

CHARLES IRA YoUNc, Jas. W. SMITH. 

